Re: 1987Johnson 6hp tiller arm photo
if I turn the throttle to the two 1/2 round markings (variable WOT area) w/ choke in 1/2 position it starts.
They are the markings that denote the correct throttle range for starting. If the throttle is set too wide then the starter mechanism should lock out,
So that all seems to be operating normally.
I don't think there is any interlock with the gear shift position. There was not in 1984.
I dont understand the bit about tilting the motor to get the gearshift to work properly. The Owners instruction book does say you should not shift the gears unless the motor is running but I don't think any harm will be caused unless you foce the lever. If it shifts between forward neutral and reverse when it is running then there is no problem.
Remember dont fix what aint broke!
The thing you should be concerned about most is a good flow of cooling water. Renew the pump impeller if in doubt. The 84 model, and the 87 model if it is the same, is inclined to restriction of the water flow at the top of the water pipe between pump and power head due to corrosion around the grommet. The flow from the pee hole must be a good strong jet of water!
You asked earlier if the ingition is coil and points or electronic. Electronic!
Do not operate the motor out of water as that will wreck the water pump impeller quicker than you can say "two shakes of a racoons tail"